WASHINGTON - With Donald Trump under fire, former Texas Gov. Rick Perry sat for an interview with Fox News' Sean Hannity on Monday night via satellite hookup, appearing by himself in the corner of a room beside a lamp, a set of books and a globe.

"I'm going to stand up to him, just like I would stand up to Vladimir Putin," Perry said, explaining his escalating war of words with the outlandish business mogul, who had attacked Perry's record of policing the southern border in Texas.

Perry, Hannity noted, seemed more willing than any of his GOP rivals to take on Trump, who has surged to the top of the Republican presidential primary polls. "There seems to be bad blood here growing," he said.

"Well, I don't know about bad blood," Perry replied, "but when he attacks me and the bullet goes through me and hits the Texas Rangers … you better believe I'm going to stand up."

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The clip of Perry alone in a corner seemed an apt visual for a candidate who has been pushing back the hardest against the Trump phenomenon, even before the reality TV star's incendiary remarks belittling the war record of U.S. Sen. John McCain, a Vietnam War POW.

"I have a message for my fellow Republicans and the independents who will be voting in the primary process," Perry said last week, before Trump scrambled the GOP contest with his shot at McCain. "What Mr. Trump is offering is not conservatism, it is Trump-ism - a toxic mix of demagoguery and nonsense."

The contrast has been particularly stark with U.S. Sen. Ted Cruz, who courted the Manhattan tycoon in his Trump Tower office last week. Since then, Cruz has steadfastly declined to join the GOP scrum over Trump's controversial remarks questioning McCain's war heroism.

"I recognize that folks in the press love to see Republican-on-Republican violence, so you want me to say something bad about Donald Trump or bad about John McCain or bad about anyone else," Cruz told reporters in Iowa. "I'm not going to do it. John McCain is a friend of mine. I respect and admire him and he's an American hero. And Donald Trump is a friend of mine."

Analysts say both Texans have been hurt by Trump, who has co-opted both of their messages on border security and immigration. He once even publicly questioned Cruz's Canadian birth.

But the new conflagration also presents opportunities. For Cruz, a Trump implosion - still by no means certain - would be a chance to reclaim the anti-Washington part of the GOP base that has rallied around Trump's no-holds-barred tactics.

"It's a bet that at some point, Trump disappears," said Southern Methodist University political scientist Cal Jillson, explaining Cruz's reluctance to go after Trump.

Cruz said in New York last week that he intends to win the GOP nomination, which means cutting into all of his rivals' support. But it is Trump, analysts say, who has done the most damage to Cruz, particularly in Iowa.

It was at Saturday's Family Leadership Summit in Ames, Iowa , where Trump made the remarks that rocked the Republican establishment and set off a media feeding frenzy.

"He's not a war hero," Trump said of McCain. "He's a war hero because he was captured…. I like people that weren't captured."

The resulting furor eclipsed almost all of the news coverage of the Family Leader event, an influential meeting of evangelicals which Cruz arguably dominated with five standing ovations.

But that is hardly the narrative that emerged from Iowa, where Trump dominated the headlines.

"He would walk Trump off the stage with an arm around his shoulder," Jillson said of Cruz. "Cruz's calling card has been, 'I'm the most energetic conservative available to you,' and Trump says, 'Not really.'"

Perry's calculation has been different. Struggling in the polls and languishing in the money race, Perry has had more reason to directly engage with Trump, now a media sensation in the GOP contest.

The billionaire's attacks on Perry have allowed the former governor to highlight his decision to send National Guard troops to the border, ostensibly to pick up the slack left by the Obama administration.

"The border security piece is a strength for Perry, and it's also very unique," said Texas GOP strategist Matt MacKowiak. And by standing up for McCain, a decorated war veteran, Perry has been offered a chance to underscore his own military service in a state with a large community of veterans.

"Frankly," Perry wrote in a National Review article on Monday, "we should expect no better from a man (Trump) who couldn't be bothered to answer the call to serve his nation when it needed him most."

For Perry, like Cruz, attacking Trump runs the risk of alienating a critical part of the GOP's activist base. But the controversy has also afforded him the moral high ground in the debate.

"Perry can do well distinguishing himself as willing to go after the bully," MacKowiak said.

What remains to be seen is how Trump fares once the dust has settled from his weekend in Iowa. He's shown no signs of backing down, and went further on Tuesday by going to South Carolina and calling one of the state's U.S. senators, presidential candidate Lindsey Graham, a "stiff" and an "idiot."

Some Republican leaders believe, hopefully perhaps, that Trump has finally crossed a line of propriety, and will soon fade in the polls. Others have yet to be convinced.

"The laws of political gravity don't appear to apply to Trump," MacKowiak said. "It's the fact that he's an anti-politician, and that's what people like about him."

Unlike traditional politicians, MacKowiack added, Trump can afford to be outrageous. It gets him attention - at the expense of everybody else - and pushes up his poll numbers. "There's an incentive for him to be outrageous."

But it was Perry, more than anyone else, who was able to garner some of Trump's space in the spotlight.

Asked what he thought of Trump's performance, Perry snapped back that he is "unfit to be Commander-in-Chief," and that he "should immediately withdraw from the race for president."